Heated pressure seaming device for plastics



Dec 18, 1951 A. M. ANDREWS 2,579,063

HEATED PRESSURE SEAMING DEVICE FOR PLASTICS Filed June '7, 1948 SILVERED SURFACE INVENTOR. ALVADORE M. ANDREWS ATTORNEY Patented Dec. 18, 1951 HEATED museum: s PLAS EAMING DEVICE FOR TICS v I Alvadorc M. Andremlortland, Oreg. v Application June 7,1948, Serial No. 31,454

2Claims. (Cl. 154 42) I This invention relates to improvements in construction of the apparatus for joining a plurality of sheets of flexible material, by introducing a thread-like carrier between the sheets to be joined, the said carrier having been drawn through a reservoir of the cement used and given a correct burden of cement for the joinder to made under heat and pressure.

It is similar to but improved over the parent application infra; the heat and the prolonged pressure being operational differences over the machine shown and claimed in my cpending application Ser. No. 747,960, filed May 14, 1947, for Apparatus and Method of Joining Pieces of Plastic, now Patent No. 2,500,053, of which this application is a continuation in part.

The objects of the invention are to increase speed of production by increasing the period of forcible contact under pressure to get as good adhesion as that which can be had by the machine oi the earlier application and at a much greater speed.

Since the solvents suitable for use in the method and apparatus are of highly volatile character and must be protected from atmosphere contact by passing the saturated thread through a tube right up to the point of inserting said thread between parts to be seamed by cementation, the additional speed makes it possible to use a smaller thread where the same is fibrous absorbent material or a smaller thread when the thread is a filament of plastic material responsive to the same solvent that seams the pieces of plastic sheet together, as the speed lessens the time during which the solvents can attack the plastic filament and reduce its tensile strength below that requisite to get it and its burden of solvent into place between the sheets to be joined or seamed. The two expressions joined or seamed, are used herein indiscriminately.

A drawing accompanies and forms a part of this specification in which- Fig. 1 is a side view, partially in section, of the seaming devices in preferred juxtaposition and operable relationship, to be explained;

Fig. 2 is an elevation of the structure of Fig. 1 taken on the plane 2-2, Fig. 1;

Fig. 3 is an enlarged view of the section of Pig. 1 taken on the plane 33, Fig. 1;

Fig. 4 is a fragmentary view of the pressure roller, showing the application of a heating element, to be explained;

Fig. 5 is a side view or the upper pressure element or roller," taken at reduced scale on the 2 I plane 5-5, Fig. 3, and broken away to show a.

.sidc view oi the heating element; and

Fig. 6 is a. partially sectioned view of the lower pressure wheel that cooperates with, the heated upper roller previously referred to, the view .being taken on the plane 6-6. Fig. 3, at reduced scale.

Describing the figures and the details thereof with greater particularity. A pressureroller I and a pressure wheel 2 are driven at synchronous speed by bevel gear sets 3 and 4 by the vertical shaft 5 and the lay-shaft 6, respectively. The pressure roller is supported by a presser foot I, movably carried by a head 8, and the pressure wheel 2 is revolubly mounted on a base-plate l0; both the head 8 and the base-plate I 0 being a part of the machine structure, the broken away parts of which are not shown but which may be ascertained, if desirable, from the parent application, the relationship being unmistakable.

A tube ll, contains a thread l2, which may either be fibrous absorbent material such as cotton or may be a filament of plastic, usually identical with that of the sheets to be joined, such as flexible vinylite plastic. The thread i2 is supplied from a ball or spool and the end first passed through a reservoir containing solvent that responsively attacks the plastic sheets to be joined and the filament of plastic if one is used for the thread i2. In case a fibrous thread is used for 12, dependence will be upon its soaking up a small quantity of the solvent, which is rapidly pulled through the tube H by feeding the thread between sheets of plastic such as !3 and M which are concurrently drawn lactween the pressure roller l and the pressure wheel 2, by operation of said roller and said wheel by operation of the bevel gear sets 3 and 4; power being applied through the vertical shaft 5, and the lay-shaft 6, from a source not shown.

When the thread i 2 is thus drawn in between the sheets of plastic l3 and H, pressure applied by the roller 1 and the wheel2, expresses solvent absorbed by the fabric thread I2 or carried in a partially dissolved outer surface, if I2 is a filament of plastic, and brings all three elements of the seam into firm contact. The roller I has a heating means to be described, which greatly assists in the making an adequate seam and the sheets pass, still held in contact, over the idle roller I 5, being supported in arcuate contact with the heated roller I by the belt It for nearly a quadrant of the surface of the roller I, as shown at I! in Fig. 1.

The pressure wheel '2, is provided with a belt traction surface supplied by a disc of resilient a recess 2?, formed by two hair-round grooves formed in the glass elements 22 and 29. Current for heating is supplied by the circuit 23, with which in series is the variable resistance 20 which, by leads 39 and 3! and the commutator rings 32 and 33, receives current irom the circuit 28 by the brushes 34 and 35.

The pressure wheel 2, preferably has a pressure ridge 88 of sumcient height and width to apply pressure of desired amount to the soaked thread I2 through the sheets, expressing its cement between the sheets. The resiliently supported belt It bears against the roller i tight enough to limit the spread of cementitious ma= terial on that side and define a straight seam.

The side parts of the roller i are preferably made of a strong synthetic of the Bakelite type and the parts held together by suitable fastenings such as the screws 38 and 39. The outside surfaces of the glass parts 22 and 23, as indicated by legend, are silvered to improve their heat directional properties and send the most of the heat towards the perimeter of the roller I, of which they form a part.

This construction permits a relatively long application of heat to the two plastic parts to be seamed, while holding them in firm contact, thus satisfying the stated objects of the invention in an excellent manner. The employment of the belt l6, holds the sheets such as l3 and H in a firm supporting grip, preventing side slip of the sheets, while their contacting surfaces are slippery with solvent, before the heat has had an opportunity to effect the firm joinder.

Having fully disclosed my invention so that those familiar with the art to which it appertains can make and use it, what I claim as new and desire to secure by Letters Patent, is:

A heated pressure searnhig device of the sol-- vent carrying thread t me wherewith two pieces of plastic are subjected to heat and premure with a solvent carrying thread between the said pieces, characterized by an upper driven revoluble pressure roller, an electrical heating ele ment embedded therein in substantial concen tricity with and of less diameter than the perimeter of the roller, and a pressure wheel supported for power drive immediately beneath said roller, the said roller having a slightly roughened surface and the wheel having a.- mating raised surface to determine the width oi the zone to which pressure is applied.

2. In an apparatus of the class described, the combination comprising a pair oi cooperating roller elements mounted for rotation about paral lel axes, means biasing the peripheries of said roller elements together, means for driving said roller elements at the same speed, said roller elements being adaptd to receive therebetween a pair of plastic sheets to be bonded together, the peripheral portion of one of said roller elements being formed of glass and having an electric. heating element imbedded therein, the inner surface of said glass portion being provided with a coating of reflective material.

ALVADORE M. ANDREWS.

REFERENCE GiElElID The following references are of record in the file of this patent:

UNITED STATES PATENTS 

